In this project we seek to define and classify hereditary tumors of the nervous system; to add to the clinical description and natural history of these diseases; to suggest methods for early diagnosis; to evaluate present modes of treatment; and to develop methods for preclinical detection and screening. Our studies have led to the recognition of at least two distinct genetic forms of neurofibromatosis: 1) the classical form as described by von\Recklinghausen, and 2) a form in which bilateral acoustic neuromas are the hallmark. We have focused on neurofibromatosis with bilateral acoustic neuroma. Efforts have been directed at improving and simplifying screening of high-risk individuals, confirming diagnosis and establishing criteria for intervention. Audiologic studies, including evaluation of auditory-evoked response and acoustic reflex decay, are useful means for early documentation and monitoring of acoustic neuroma. In our first major study involving neurofibromatosis of the von\Recklinghausen type, a multidisciplinary program is in progress to evaluate neurologic and cognitive status in these patients compared to their unaffected sibs. Initiation of gene linkage studies, so successful in Huntington disease, awaits availability of modest funds, primarily for travel.